Person‐centered care (PCC) delivery and co‐creation of care (establishing productive patient‐professional interaction) are expected to lead to better patient outcomes. Given the prominent role of informal caregivers in care delivery processes to persons with intellectual disabilities (PWID), they are expected to benefit from person‐centered care (PCC) and co‐creation of care as well. This study aims to identify the relationship between PCC, co‐creation of care and outcomes among informal caregivers of PWID. A cross‐sectional survey was conducted in 2015 among informal caregivers of PWID (45.8% parents, 44.1% siblings, 10.1% other family member). All PWID were living in residential homes of a long‐term care organization in the Eastern part of the Netherlands. For every PWID, the most important informal caregiver was invited to participate. Nine hundred and forty‐one invitations were sent out and 289 of them responded (31% response rate). Mean age of informal caregivers was 61.80 (SD 11.21; range 23–90) years old. About half of the respondents (55%) were female and 23% were single. Most of the respondents (83%) were providing informal care for more than 10 years and 29% provided informal care for 8 hours per week or more. Correlation analyses indicated that PCC and co‐creation of care were positively related to informal caregivers' satisfaction with care and their own well‐being. Regression analyses showed that PCC is associated with satisfaction with care (β = 0.60, p < 0.001) and well‐being (β = 0.22, p < 0.01) while controlling for background characteristics. Relational co‐creation was also positively associated with satisfaction with care (β = 0.15, p < 0.01) and well‐being (β = 0.20, p < 0.01). This study provided the first empirical evidence that PCC and co‐creation of care matter for satisfaction with care and the well‐being of informal caregivers of PWID.